MICROBIOTE: Vitamin D is what activates it

Vitamin D is known to take many different forms, but standard blood tests only detect its inactive precursors (ergocalciferol + cholecalciferol) stored by the body. To use vitamin D, the body must metabolize these precursors into an active form. However, this research shows for the first time that the gut microbiota also determines active vitamin D levels. “We are surprised to find that microbiome diversity is closely associated with the active vitamin D, but not with the precursor form,” says lead author Dr. Deborah Kado, UC San Diego Health’s head of osteoporosis. .

Greater diversity of the microbiome and more vitamin D.

Gut microbiome diversity is known to be associated with overall better health. Many studies have also suggested that people with low vitamin D levels are at increased risk for cancer, heart disease, severe forms of COVID-19, and other diseases.

It is the active form “that counts”! A large randomized clinical trial, conducted among more than 25,000 adult participants, previously concluded that taking vitamin D supplements has no effect on health, heart disease, cancer, or even bone health. . The authors speculate that these earlier studies only measured the precursor form of vitamin D, rather than its active form: “Measures of vitamin D formation and degradation may be better indicators of underlying health problems that could potentially respond to vitamin D supplementation.”

Here, RNA sequencing analysis of stool and blood samples provided by 567 men participating in the MrOS (National Institute on Aging) funded study of osteoporotic fractures in men, with a mean of 84 years, mostly in good or excellent health, reveals:

• a link between active vitamin D and overall microbiome diversity;
• 12 special types of bacteria most abundant in the gut microbiomes of participants with high levels of vitamin D: most of these 12 bacteria produce butyrate, a beneficial fatty acid that contributes to gut health;
• the association is strong, despite the great variability and complexity of the participants’ gut microbiomes and their exposure to the sun.

“It seems that no matter how much vitamin D you get from sun exposure or supplementation, no matter how much the body can store, the body’s ability to metabolize this vitamin into active vitamin D is critical. This is what clinical trials need to measure to get a more accurate picture of the vitamin’s role in health ”.

Further studies are needed to better understand the role of bacteria in vitamin D metabolism and to determine whether a microbiome-level intervention could optimize treatments for bone health.